Radio frequency identification (RFID) tags are well known in the prior art. RFID tags come in many forms but all comprise an integrated circuit on which, in use, data can be stored and a coil which enables it to be interrogated by a reader that also powers it by means of an inductive (wireless) link. Generally RFID tags are quite large, due to the frequency they operate at (13.56 MHz) and the size of coil they thus require, and operate over large ranges and have very small storage capacity. Smaller RFID tags have also been developed, operating at various frequencies, but still having small storage capacity. Some RFID tags include read-only memory (ROM) and are written to at the time of manufacture, whilst others have read and write capability.
A memory tag may generally be considered to be a transponder device with significant memory—sufficient to store significant digital content rather than just identifier data. A memory tag is thus generally more sophisticated than a conventional RFID tag (containing typically a short piece of data primarily useful to provide an identifier alone), and may incorporate a number of elements. A particularly useful form of memory tag operates inductively by provision of RF power in a similar manner to an RFID tag. Such memory tags may include an antenna which couples inductively with an antenna in a tag reader, an RF decoder for decoding radio frequency signals received via the antenna, logic for processing the received signal and an area of non-volatile memory. Memory tags may also include an RF coder for coding data to be transmitted from the tag to the reader.
Data stored in memory tags is accessible by a reader device, which powers up the tag and causes stored information to be output. Any person with access to a reader may access this information by bringing that reader into close proximity with the memory tag whether or not they are authorised to do so even when the data that is stored is of a sensitive or confidential nature. Further, any person with access to a memory tag write device, such as a memory tag reader with write capability, may access and change the information stored on a memory tag, or may copy the information stored on one memory tag onto another tag, thereby providing a duplicate memory tag.
An issuer of memory tags seeking a high level of confidence of the authenticity of the identity of the tags that are presented to it (for example, enabling an establishment that issues memory tags to members as entry access devices to have a high degree of certainty that tags presented to it for access to the establishment are tags issued by the establishment) may manufacture and provide to that establishment memory tags having an architecture that are unique to that establishment.